Anchoring system for injection molded magnets on a flux ring or motor housing

ABSTRACT

A power tool includes a flux ring with an annular member. At least one molded magnet is received on the annular member. An anchor is on the annular member to retain the at least one magnet on the annular member. The anchor is unitarily formed with the annular member to receive the magnet. The anchor includes at least one bend with a reinforcement member at the at least one bend.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This patent application is a continuation-in-part application ofU.S. application Ser. No. 09/492,059 filed Jan. 27, 2000 entitledANCHORING SYSTEM FOR INJECTION MOLDED MAGNETS ON A FLUX RING OR MOTORHOUSING, the specification and drawings of which are herein expresslyincorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] The present invention relates to power tools and, moreparticularly, to motors for power tool flux rings with anchors to retainmolded magnets on the flux ring.

[0003] In motor construction, the motor magnets must be retained on thehousing or separate flux ring within the housing. Ordinarily, thesemagnets have been glued or adhered to the metallic ring or housing. Inadhering the magnets to the metallic surface so that the magnets do notshift during use, various types of adhesives have been used. While someof the adhesives have been satisfactory, some adhesives work better thanothers. As the adhesives age, it is possible that if the power tool isdropped, that the sudden shock will destroy the bond between the magnetand the housing or ring, enabling the magnet to travel within the motor.When this occurs, the motor ceases to function. Thus, it would bedesirable to provide a mechanism to retain the magnets in position onthe ring or housing.

[0004] The present invention provides the art with a mechanism to retainmagnets onto a flux ring or motor housing. Due to the advent of moldedmagnets, it is possible to provide an anchor in the flux ring or housingto retain the molded material on the ring or housing. One such anchoringmember is an aperture having a counter-sink on the exterior of the ringor housing. Thus, when the magnet is molded onto the ring, the magneticmaterial that passes through the ring into the counter-sink forms asolid rivet-shaped fastener. Also, anchors may be stamped out of thering or housing and project into the interior of the ring to receive themolded magnetic material. The anchors include gussets to reinforce thebend points to enhance the strength of the anchors and help resistdeformation during molding. Due to the anchors being unitarily formed orstamped from the ring or housing, an aperture is left in the ring orhousing after stamping, which is likewise filled with the moldedmagnetic material.

[0005] In accordance with a first aspect of the invention, a flux ringcomprises an annular housing. At least one molded magnet is received onthe housing. An anchor on the housing retains the at least one magnet onthe annular housing. The anchor is unitarily formed with the housing.The anchor includes at least one bend. A reinforcement member ispositioned at the bend to strengthen the anchor. The annular housing ismetal with the anchor projecting radially from the housing. Theprojecting anchor has an aperture immediate the anchor on the housing.Thus, the magnetic material molds around the anchor and into theaperture. The anchor may have several different shapes. Preferably, theanchor has a rectangular shape, with one or both ends connected to thehousing. Also, the anchor may have an L- or T-shape with one endconnected to the housing.

[0006] In accordance with a second aspect of the invention, a motorcomprises a stator assembly with the stator assembly including a fluxring. The flux ring comprises an annular housing. At least one moldedmagnet is received on the housing. An anchor on the housing retains theat least one magnet on the annular housing. The anchor is unitarilyformed with the housing. The anchor includes at least one bend. Areinforcement member is positioned at the bend to strengthen the anchor.The annular housing is metal with the anchor projecting radially inwardfrom the housing. The projecting anchor has an aperture immediate theanchor on the housing. Thus, the magnet molds around the anchor and intothe aperture. The anchor may have several different shapes. Preferably,the anchor has a rectangular shape, with one or both ends connected tothe housing. Also, the anchor may have an L- or T-shape with one endconnected to the housing. Also, the motor comprises an armaturerotatable within the stator assembly. A commutator is rotatable with thearmature and connected to the armature via a shaft. A brush assembly isassociated with the commutator.

[0007] In accordance with a third aspect of the invention, a power toolcomprises a housing with a motor in the housing. The motor comprises astator assembly with the stator assembly including a flux ring. The fluxring comprises an annular housing. At least one molded magnet isreceived on the housing. An anchor on the housing retains the at leastone magnet on the annular housing. The anchor is unitarily formed withthe housing. The anchor includes at least one bend. A reinforcementmember is positioned at the bend to strengthen the anchor. The annularhousing is metal with the anchor projecting radially inward from thehousing. The projecting anchor has an aperture immediate the anchor onthe housing. Thus, the magnet molds around the anchor and into theaperture. The anchor may have several different shapes. Preferably, theanchor has a rectangular shape, with one or both ends connected to thehousing. Also, the anchor may have an L- or T-shape with one endconnected to the housing. Further, the anchor may have a truncated coneshape with an axial aperture through the cone. Also, the motor comprisesan armature rotatable within the stator assembly. A commutator isrotatable with the armature and connected to the armature via a shaft. Abrush assembly is associated with the commutator. Also, the power toolincludes an output member coupled with the motor shaft. An actuatormember is electrically coupled between the motor and the power source toenergize and de-energize the motor. In turn, when the motor isenergized, the output member rotates.

[0008] Additional objects and advantages of the present invention willbecome apparent from the detailed description of the preferredembodiment, and the appended claims and accompanying drawings, or may belearned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 illustrates a cross-section view of a power tool inaccordance with the present invention.

[0010]FIG. 2 illustrates a perspective view of a flux ring in accordancewith the present invention.

[0011]FIG. 3 is a cross-section view through FIG. 2 along line 3-3thereof.

[0012]FIG. 4 is a perspective view of a flux ring like that illustratedin FIG. 2 with the magnets removed.

[0013] FIGS. 5-8 illustrate perspective views of additional embodimentsof flux rings in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Turning to FIG. 1, a power tool in accordance with the presentinvention is illustrated and designated with the reference numeral 10.The power tool 10 is illustrated as a drill; however, any type of powertool such as a screwdriver, sander, rotary tool, clippers, saw or thelike which utilize an electric motor may be used with the motor of thepresent invention. The power tool 10 includes a housing 12 whichsurrounds a motor 14. An activation member 16 is coupled with the motor14 as well as with a power source 18. The power source 18 may be a powercord (AC current) or the power tool may have a battery (DC current) asshown. The motor 14 is coupled with an output 20 which may include atransmission 22 and a chuck 24 to retain a tool (not shown) with thedrill.

[0015] The motor 14 includes a stator assembly 30 which includes ahousing 32, flux ring 34, and magnets 36 and 38. An armature 40 includesa shaft 42, a rotor 44 with laminations 46 and windings 48, as well as acommutator 50 coupled with the shaft 42. The motor also includes endplates 52 and 54. End plate 52 includes a bearing 56 which balances oneend of the shaft 58 which is coupled with a pinion 60 which is part ofthe power tool output. Brushes 62 and 64 which are associated with thecommutator 50. A bearing 70 is also coupled with the end cap to balancerotation of the shaft 42.

[0016] Turning to FIG. 2, the flux ring 34 is illustrated with magnets36 and 38. The magnets 36 and 38 are of a molded magnetic material.Preferably, the molded material is an injection molded material. Thering 34 is positioned within a die and the magnetic material is moldedonto the flux ring. Also, the housing 32 may be used as the flux ring.Thus, the discussion with respect to the ring 34 may equally apply tothe metallic housing 32 of the motor 14.

[0017] The flux ring 34 includes anchors 80 to retain the magnets 36 and38 onto the ring 34. The anchors 80 may be of two types. First, anchor82 is an aperture formed in the housing 34. The aperture 82 has a firstportion 84 and a second counter-sink portion 86. The counter-sinkportion 86 extends to the exterior 88 of the ring 34. Thus, as seen inthe cross-section in FIG. 3, as the molded magnetic material is receivedin the aperture 82, the molded material has a neck 92 and a head 94. Thehead 94 and neck 92 provide an overall rivet appearance, thus the largehead 94 acts to retain the magnet 36, 38 on the ring 34. The ring 34 maybe comprised of just a plurality of aperture anchors 82 to retain themagnets on the ring 34.

[0018] Additional anchors 96 may be utilized on the ring. Anchors 96project from the interior surface 98 of the ring 34. Ordinarily, theanchors 96 are stamped or the like into the ring 34 forming an aperture100 immediately adjacent the projecting anchor 96. Thus, when the moldedmagnetic material forms around the projecting anchor 96, it likewisegoes under the anchor 96 and fills in the aperture 100. This provides afirm securement for the magnet onto the ring 34.

[0019] The ring 34 illustrated in FIG. 2 is illustrated in FIG. 4without the magnetic material. As can be seen, the projecting anchor 96has an overall rectangular shape with ends 102 and 104 unitarily formedwith the ring 34. The anchor has bends 106, 108 between the legs 110,112 and web 114. A reinforcement gusset 116 is positioned at the bends106, 108. The reinforcement gusset 116 strengthens the anchor during themolding process to maintain its shape. The reinforcement gusset 116 maybe a dimple or indent at the bend. Likewise, the aperture anchors 82 areillustrated in FIG. 4. Also, aperture anchors 82 could be removed andonly radially projecting anchors 96 would be used to retain the magnetson the housing.

[0020] The rings 34 are ordinarily formed from a rectangular stampedsheet material. The rectangular shaped sheet metal is stamped to formthe apertures 82 or the projecting anchors 96 including thereinforcement gussets 116, or both, depending upon which anchoringsystem is desired. The flat sheet metal part is then rolled into anannular ring and may have a butt joint 99 (as shown), meshing end 101(as seen in FIG. 6), or the like, forming the ring. The ring is thenplaced within a die where the magnetic material is injection molded ontothe ring. The injection molded material moves through the apertures 82and around the projecting anchors 96 as illustrated in FIG. 3. Then thering is removed from the die, it is ready for insertion into the motorhousing. Likewise, the motor housing itself could be utilized as thering. In this case, the ring would not be present and the magnets wouldbe molded directly onto the housing with the housing being formed asdescribed.

[0021] Moving to FIGS. 5-8, additional embodiments of the presentinvention are illustrated. In FIG. 5, the flux ring 34′ includesoptional aperture anchors 82 like those previously described. Here, theprojecting anchors 120 have an overall rectangular shape with one endsecured to the ring 34′. The reinforcement gusset 116 is formed at thebend. Also, aperture 122 is immediately adjacent the projecting anchor120.

[0022] Moving specifically to FIG. 6, another ring 34″ is shown. Here,the ring 34″ includes optional aperture anchors 82 like those previouslydescribed. Here, the projecting anchor 130 has an overall L-shape. Theprojecting L is secured at one end to the ring 34″. The reinforcementgusset 116 is formed near the ring 34″. The aperture 132 immediatelyadjacent the projecting L-shaped anchor 130 likewise has an L-shape.

[0023] Turning to FIG. 7, an additional embodiment is shown. Here, thering 34″′ includes optional aperture anchors 82 like those previouslydefined, as well as projecting anchors 140. The projecting anchors 140have an overall rectangular shape and are angled inward directly out ofthe ring 34″′. The reinforcement gusset 116 is formed near the ring34″′. Also, the aperture 142 is immediately adjacent the projectinganchor 140.

[0024]FIG. 8 illustrates an additional embodiment of the presentinvention. The flux ring 34″″ includes optional aperture anchors 82 likethose previously defined. The projecting anchors 160 have an overallT-shape. The apertures 162 immediately adjacent the T-shaped projectingmember 160 likewise have a corresponding T-shape. The reinforcementgusset 116 is formed near the ring 34″″. Thus, as the magnetic materialis molded onto the ring, the T-shaped projection 160 is covered by themagnetic material while the T-shaped aperture 162 receives magneticmaterial both holding the magnets in place on the ring 34″″.

[0025] While the above detailed description describes the preferredembodiment of the present invention, the invention is susceptible tomodification, variation, and alteration without deviating from the scopeand fair meaning of the subjoined claims.

What is claimed is:
 1. A flux ring, comprising: an annular housing; atleast one molded magnet received on said housing; and an anchor on saidhousing retaining said at least one magnet on said annular housing, saidanchor unitarily formed with said housing and including a bend and areinforcing member positioned at said bend.
 2. The flux ring accordingto claim 1 , wherein said annular housing being metal.
 3. The flux ringaccording to claim 2 , wherein said anchor projects radially from saidhousing.
 4. The flux ring according to claim 3 , wherein said anchor isformed from said housing and providing an aperture immediate saidanchor.
 5. The flux ring according to claim 4 , wherein said magnetmolds around said anchor and into said aperture.
 6. The flux ringaccording to claim 3 , wherein said anchor has an overall rectangularshape with two ends connected to said housing with reinforcement membersat bends.
 7. The flux ring according to claim 6 , wherein one end isconnected to said housing.
 8. The flux ring according to claim 3 ,wherein said anchor has an overall L-shape with one end connected tosaid housing.
 9. The flux ring according to claim 3 , wherein saidanchor has an overall T-shape with one end connected to said housing.10. A motor comprising: a stator assembly, said stator assemblyincluding a flux ring comprising: an annular housing; at least onemolded magnet received on said housing; an anchor on said housingretaining said at least one magnet on said annular housing, said anchorunitarily formed with said housing and including a bend, a reinforcementmember positioned at said bend; an armature rotatable within said statorassembly; a commutator rotatable with said armature and connected tosaid armature via a shaft; and brush assemblies associated with saidcommutator.
 11. The motor according to claim 10 , wherein said annularhousing being metal.
 12. The motor according to claim 11 , wherein saidanchor is projecting radially inward from said housing.
 13. The motoraccording to claim 12 , wherein said anchor is a portion of said housingand having an aperture immediate said anchor.
 14. The motor ringaccording to claim 13 , wherein said magnet molds around said anchor andin said aperture.
 15. The motor according to claim 12 , wherein saidanchor has an overall rectangular shape with two ends connected to saidhousing with reinforcement members at the bends.
 16. The motor accordingto claim 15 , wherein one end is connected to said housing.
 17. Themotor according to claim 12 , wherein said anchor has an overall L-shapewith one end connected to said housing.
 18. The motor according to claim12 , wherein said anchor has an overall T-shape with one end connectedto said housing.
 19. A power tool comprising: a housing; a motor in saidhousing, said motor comprising: a stator assembly, said stator assemblyincluding a flux ring comprising: an annular housing; at least onemolded magnet received on said housing; an anchor on said housingretaining said at least one magnet on said annular housing, said anchorunitarily formed with said housing and including a bend, reinforcementmember at said bend; an armature rotatable within said stator assembly;a commutator rotatable with said armature and connected to said armaturevia a shaft; brush assemblies associated with said commutator; a powersupply; an output member coupled with said motor shaft; and an actuatormember electrically coupled between said motor and said power source forenergizing and de-energizing said motor which, in turn, rotates saidoutput member when said motor is energized.
 20. The power tool accordingto claim 19 , wherein said annular housing being metal.
 21. The powertool according to claim 20 , wherein said anchor is projecting radiallyinward from said housing.
 22. The power tool according to claim 21 ,wherein said anchor is a portion of said housing and having an apertureimmediate said anchor.
 23. The power tool according to claim 22 ,wherein said magnet molds around said anchor and in said aperture. 24.The power tool according to claim 21 , wherein said anchor has anoverall rectangular shape with two ends connected to said housing withreinforcement members at the bends.
 25. The power tool according toclaim 24 , wherein one end is connected to said housing.
 26. The powertool according to claim 21 , wherein said anchor has an overall L-shapewith one end connected to said housing.
 27. The power tool according toclaim 21 , wherein said anchor has an overall T-shape with one endconnected to said housing.